Wesker ist in den früheren Teilen ja schon "ein Bösewicht" der für Umbrella arbeitet. In Code Veronica taucht er obwohl er eigentlich tot sein sollte wieder auf, und will einen Virus von der Umbrella Corp stehlen. Was für eine Rolle genau er in RE4 spielt, erfährt man glaub ich nur durch das freigespielbare Minigame "Seperate Ways" auf der PS2-Version(Also ich könnte´s dir sagen, ist nichts großartiges, aber spiel erstma durch
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Achso, zu Ada: (wusste ich selber nicht, habe Resident Evil frühe rnicht gespielt) "Ada would make her first actual on-screen appearance in Resident Evil 2, serving as the partner character in Leon S. Kennedy's half of the storyline and serves as a playable during certain gameplay portions. Under the guise of an ordinary citizen, she requests Leon's aid, claiming to be looking for her missing fiancée in Raccoon City. However, she learns that John died during the "Mansion Incident" (the events of the first game) and attempts to escape the city together with Leon. Through the course of the story, she develops romantic feelings for Leon, but gets injured during a battle against the mutated William Birkin. Later it is revealed that Ada is actually a spy for an unnamed organization, sent to retrieve the G-Virus sample. She does not escape with Leon and the others and is presumed dead at the outcome of the game. Her on-screen death differs depending on the order in which order Leon's half of the game is played. In the Leon A scenario, she confronts Leon before being shot by Annette Birkin and falls into her death from a catwalk. In the Leon B scenario, she confronts the mass-produced Tyrant, before being mortally wounded and dying from massive blood loss. Despite her apparent death in either case, she comes out from the shadows to help the player's character near the end of the second scenario by providing the rocket launcher needed to destroy the Super Tyrant. Ada is also a fully playable character in the "Extreme Battle" minigame added to later versions of the game, which has not bearing to the plot.
A character-specific epilogue in Resident Evil 3: Nemesis does confirm her survival and Wesker's Report, a fictional documentary published to promote the release of Resident Evil Code: Veronica X expands on Ada's role in Resident Evil 2. The organization Ada works for is revealed to be the same that hired Albert Wesker in Code: Veronica. Moreover, Wesker worked alongside Ada from behind-the-scenes to retrieve the G-Virus and it was him who saved her life."(wikipedia)
